1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and in particular to a semiconductor device and a method of manufacturing the same using tungsten, titanium, or titanium nitride as a material for wiring and the like.
2. Description of Related Art
Presently for the wet cleaning of silicon substrates in the manufacturing process for semiconductor devices, RCA cleaning is generally used. This RCA cleaning uses a hydrogen peroxide-sulfuric acid mixture (SPM), an ammonia-hydrogen peroxide mixture (APM), a hydrochloric acid-hydrogen peroxide mixture (HPM), or hydrofluoric acid (HF). Of these chemical solutions, SPM and HPM remove mainly metallic impurities from silicon substrates through oxidation, APM removes particles and organic impurities through lifting-off and decomposition by etching, and HF removes metallic impurities and natural oxides. In order to enhance impurity removal, SPM, APM, and HPM are used under a high temperature or a high concentration.
Heretofore, since the RCA cleaning described above has been applied to processes before metallic wiring, materials exposed on the surface of the silicon substrates and in direct contact with such chemical solutions have been limited to silicon and the compounds thereof. In processes before metallic wiring, on the other hand, when a structure consisting of tungsten (W), titanium (Ti), or titanium nitride (TiN) is fabricated on a silicon substrate, RCA cleaning must be carried out under conditions where these materials are exposed on the surface of the substrate. Of the chemical solutions for RCA cleaning, however, since hydrogen peroxide, sulfuric acid, and hydrofluoric acid have properties to dissolve W, Ti and TiN, and Ti, respectively, if these materials are exposed on the silicon substrates, there is a problem that these metals are dissolved by conventional RCA cleaning.
As described above, when a semiconductor device is manufactured using a conventional cleaning method, since cleaning is carried out under conditions where W, Ti, and TiN are exposed, there has been a problem that these metals are dissolved.
It is therefore an object of the present invention to provide a semiconductor device manufactured through cleaning without dissolving W, Ti, or TiN even if these metallic materials exposed on the substrates to be cleaned, and a method for manufacturing such a semiconductor device.
According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising: an interlayer insulation film forming step for forming an interlayer insulation film on a silicon substrate; a barrier metal depositing step for depositing a barrier metal on said interlayer insulation film; a step for depositing a tungsten film on said barrier metal; a first cleaning step for cleaning said silicon substrate by dipping said silicon substrate in a solution of at least one selected from a group consisting of HF, HCl, and NH4OH; a step for forming a photoresist pattern on said tungsten film; and a patterning step for patterning said tungsten film and said barrier metal using said photoresist pattern as a mask.
According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising: a step for forming an interlayer insulation film on a silicon substrate; a step for forming an opening in said interlayer insulation film; a step for depositing a barrier metal on said interlayer insulation film including in said opening; a step for depositing a tungsten film on said barrier metal; a first cleaning step for cleaning said silicon substrate by dipping said silicon substrate in a solution of at least one selected from a group consisting of HF, HCl, and NH4OH; a step for forming a photoresist pattern on said tungsten film; and a patterning step for patterning said tungsten film and said barrier metal using said photoresist pattern as a mask.
According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising: an interlayer insulation film forming step for forming an interlayer insulation film on a silicon substrate; a step for forming an opening in said interlayer insulation film; a step for forming a polysilicon plug by depositing polysilicon in said opening; a step for forming cobalt silicide on the upper end of said polysilicon plug by the salicide process; a step for depositing a barrier metal on said interlayer insulation film including said cobalt silicide; a tungsten film depositing step for depositing a tungsten film on said barrier metal; a step for forming a photoresist pattern on said tungsten film; and a patterning step for patterning said tungsten film and said barrier metal using said photoresist pattern as a mask.
According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising: a step for forming an interlayer insulation film on a silicon substrate; a step for forming an opening in said interlayer insulation film; a step for depositing a barrier metal on said interlayer insulation film including in said opening; a step for depositing a tungsten film on said barrier metal; a first cleaning step for cleaning said silicon substrate by dipping said silicon substrate in a solution of at least one selected from a group consisting of HF, HCl, and NH4OH; and a planarizing step for planarizing said tungsten film, said barrier metal, and said silicon oxide film by polishing.
According to a fifth aspect of the present invention, there is provided a semiconductor device comprising: a silicon substrate; an interlayer insulation film formed on said silicon substrate; a polysilicon plug formed by depositing polysilicon in an opening formed in said interlayer insulation film; a wiring part formed on the upper end of said polysilicon plug, said wiring part having a barrier metal formed in contact with said polysilicon plug, and a tungsten film deposited on said barrier metal; and cobalt silicide formed between the upper end of said polysilicon plug and said barrier metal, wherein said cobalt silicide prevents the dissolution of said polysilicon plug in the chemical solution for removing impurities present on the surface of said silicon substrate.
According to a sixth aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising: an interlayer insulation film forming step for forming a first interlayer insulation film on a silicon substrate; a step for forming an opening in said first interlayer insulation film; a step for forming a polysilicon plug by depositing polysilicon in said opening; a step for forming a second interlayer insulation film on said polysilicon plug and said first interlayer insulation film; a step for forming an opening in said second interlayer insulation film on said polysilicon plug; a step for forming cobalt silicide on the upper end of said polysilicon plug by the salicide process; a step for depositing a barrier metal on said cobalt silicide and said second interlayer insulation film; a tungsten film depositing step for depositing a tungsten film on said barrier metal; a step for forming a photoresist pattern on said tungsten film; and a patterning step for patterning said tungsten film and said barrier metal using said photoresist pattern as a mask.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.